Patent GB-684154-A (GB)
Title: Improvements in or relating to machines for injection moulding, transfer moulding, or pressure casting
IPC: B29C45/70
Filed: 1949-01-10
Abstract: 684,154. Injection and transfer moulding machines. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. Jan. 10, 1949 [Jan. 13, 1948], No. 655/49. Class 87 (ii). [Also in Groups XXII and XXIX] In an injection moulding, transfer moulding or pressure casting machine the movable parts, e.g. mould parts, injection cylinder and injection plunger, are actuated by double-acting reciprocatory members having two different areas acted upon by a constant and a varying pressure for moving them to inoperative and operative positions respectively, and automatically operated means are provided whereby increased pressure from an independent source acting in the same sense as the varying pressure is brought to bear on the parts during the injection or transfer operation. In the machine of Fig. 1 an upper mould part 7 is fixed to a fixed frame 1, 2, 3 and a lower mould part 6 on a platen 5 is movable into engagement with the part 7 by an hydraulic piston 4. The platen 5 is moved down by pistons 18 in cylinders 19. An injection cylinder 17 is slidable on the rods 3 of the frame and may be moved down into engagement with the mould part 7 by an hydraulic piston 13. The injection plunger 10 is moved down by piston 11. High pressure from line 22 permanently acting on pistons 18 and on the underfaces of pistons 11 and 13, constantly urges the piston mould part 6, and the injection cylinder and plunger to their inoperative positions. The spaces 23, 24, 25 below piston 4 and above pistons 11 and 13 are connected to a conduit 26 leading to valve casing 27 (Fig. 1a). The casing is supplied with high pressure fluid from line 11 at XX (Fig. 1a) and with fluid from a varying pressure source at XOX. XXX leads to exhaust which may be at atmospheric or other suitable low pressure. When lever E is operated to open valve D, as shown, and close valve B pressure from line XOX is supplied to pistons 4, 11 and 13 via check valve C and line 26. The areas of the pistons are such that piston 4 first moves to close the mould whereupon the pressure rises and piston 13 moves to bring the injection cylinder 17 into engagement with the mould part 7, the pressure then rising again to bring down injection plunger 10. When the plunger 10 contacts material in the cylinder 17 the pressure again rises until it is sufficient, acting in conjunction with the high pressure, to raise valve A against spring F, admitting high pressure to line 26 for the injection operation and closing check valve C. The high pressure acts on the central part and the varying pressure on the annular part of the end face of valve A. After injection, lever E is operated to close valve D and open valve B, opening line 26 to exhaust and allowing valve A to close to isolate the high pressure system. The various movable parts are then returned to their inoperative positions by the high pressure. Fig. 3 (not shown), shows a transfer moulding machine similar to Fig. 1 with the injection cylinder and associated parts omitted. A passage is formed in the upper mould part into which moulding material placed on the lower mould part enters when the mould closes and from which it is injected into the mould cavities by the injection plunger. The Specification also refers to constructions in which certain parts move in the same instead of opposite senses and in which the differential pistons are replaced by multiple pistons acting through yokes. The machines may be either vertical or horizontal. The Specification as open to inspection under Sect. 91, states that the forces urging the movable parts to their inoperative positions may be derived from springs or weights. This subjectmatter does not appear in the Specification as accepted.